Abstract: An insulating and protective structure for frozen substrates wherein a hydrophobic or water impermeable base layer is applied first to the substrate and successive layers of a polyurethane foam or similar synthetic plastic foam material are foamed in place on the base layer, each of said foam layers having a vapor penetration-resistant layer on its upper surface and below the next layer of foam. Finally, there is applied a hydrophobic or water impermeable layer to the upper surface of the uppermost vapor penetration-resistant layer.This structure is designed particularly for application to substrates underlain with permafrost in the Arctic and sub-Arctic regions. It is designed to provide moisture penetration resistance, low thermal conductivity and to have both high compressive and flexure strength in order to impede heat transfer even with consequent freeze-thawing of the frozen substrate and likewise prevent physical damage to the surface of the substrate.

Abstract: a culvert construction particularly useful in Arctic regions wherein a permafrost condition typically prevails is provided by a culvert having an insulating base layer between the culvert and the permafrost, preferably wherein the base layer is of greater width than the width of the culvert. Suitable materials for preparing the insulating base layer are synthetic resin foams such as polyurethane and polystyrene. The culvert construction is useful in Arctic regions where a permafrost condition prevails to inhibit culvert sag and culvert icing.